I stick with the 24/0 for the whole seedling/veg... it's a short season, work those plants! After 2-3 months of veg I cut the lights to 18/6 for less than a week (and change over 25% of the lights from "grow" to "bloom.") After that it's 12/12 with 75%-100% of the lights on "bloom" instead of "grow"